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Radio Clock

I would like to have a big clock and precise in the living room. So I buyed big four 7 segments LED displays (56,9mm) Kingbright with common anod SA23-12SRWA. I used a DCF77 modul and a microcontroller Atmega16. The four displays were multiplexed and drived with UDN2981. Also I needed a Darlington array ULN2803A to turn on the display because of the small current allowed by the Atmega16 outputs.

The Atmega16 has three timers and I tought one timer I can use to decode an IR signal sent from a TV-remote. To decode a modulated (36KHz) TV-remote signal we need an IR-receiver for example TSOP3236. I wrotte the decoding routine in the timer interrupt function which analyse the signal conform RC protocol.

Also I added an PIR sensor to the clock with the purpose to save energy. After 30 seconds the display are turned off, but if a person stays in fron of the clock, the PIR sensor with detect the body temperature and turn the displays on, to see the actual time.

So looks the first version of my PCB:

Here you can see the radio clock in action:


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